NIEHS is leading a National Institutes of Health (NIH) long term study looking at the potential health effects of the oil spill in various responder populations. During FY 2015, the GuLF STUDY (Gulf Long-term Follow-Up Study) actively conducted the follow-up interviews. Additionally, NIEHS investigators are in the midst of inviting 6,200 English-speaking cohort members from within 60 miles of clinics in New Orleans, LA or Mobile, AL to take part in clinical examinations for the Biomedical Surveillance Sub-Cohort, in hopes of completing exams with 3,500 to 4,000 participants. Participants undergo comprehensive lung function testing and be asked to complete a battery of behavioral and physiological tests to assess neurological function. Biological samples will be collected to assess immune, renal, and kidney function. Smaller clinical sub-studies, such as assessing temporal changes in stress hormones through collection of repeat saliva samples, are also included. Finally, participants complete a comprehensive clinical mental health assessment which includes questionnaire modules to assess traumatic events and substance abuse as well as questions designed to assess mental health services utilization by participants. In the meantime, NIEHS investigators are working to evaluate all of the available environmental and occupational exposure monitoring data in order to more completely characterize exposures in the study population. Ongoing statistical modeling will lead to the development of cleanup-task specific exposure matrices that will allow assignment of exposure estimates for volatile compounds and other exposures related to oil spill cleanup. Approaches and preliminary results from exposure characterization efforts were presented at national and international meetings. Cleaning and analysis of the baseline data has begun and we will be reporting findings at scientific meetings and writing up the results for publication in peer-reviewed journals.